$(function () {
        const models = [
            {id: 1, title: 'hello', parent: 0},
            {id: 3, title: 'hello', parent: 1},
            {id: 4, title: 'hello', parent: 3},
            {id: 5, title: 'hello', parent: 4},
            {id: 2, title: 'hello', parent: 0},
            {id: 6, title: 'hello', parent: 4},
            {id: 7, title: 'hello', parent: 3},
            {id: 8, title: 'hello', parent: 10}
        ];
        const nestedStructure = getNestedChildren(models, 0);
        console.log(nestedStructure);
    })
 
    function getNestedChildren(arr, parent) {
        var out = []
        for (var i in arr) {
            if (arr[i].parent == parent) {
                var children = getNestedChildren(arr, arr[i].id)
                if (children.length) {
                    arr[i].children = children
                }
                out.push(arr[i])
            }
        }
        return out
    }

<template>
  <el-tree
    :data="treeData"
    :props="defaultProps"
    accordion
    @node-click="handleNodeClick">
  </el-tree>
</template>
 
<script>
    export default {
        name: "Test",
      data(){
        return {
          data : [
            {id:1,parentId:0,name:"一级菜单A",rank:1},
            {id:2,parentId:0,name:"一级菜单B",rank:1},
            {id:3,parentId:0,name:"一级菜单C",rank:1},
            {id:4,parentId:1,name:"二级菜单A-A",rank:2},
            {id:5,parentId:1,name:"二级菜单A-B",rank:2},
            {id:6,parentId:2,name:"二级菜单B-A",rank:2},
            {id:7,parentId:4,name:"三级菜单A-A-A",rank:3},
            {id:8,parentId:7,name:"四级菜单A-A-A-A",rank:4},
            {id:9,parentId:8,name:"五级菜单A-A-A-A-A",rank:5},
            {id:10,parentId:9,name:"六级菜单A-A-A-A-A-A",rank:6},
            {id:11,parentId:10,name:"七级菜单A-A-A-A-A-A-A",rank:7},
            {id:12,parentId:11,name:"八级菜单A-A-A-A-A-A-A-A",rank:8},
            {id:13,parentId:12,name:"九级菜单A-A-A-A-A-A-A-A-A",rank:9},
            {id:14,parentId:13,name:"十级菜单A-A-A-A-A-A-A-A-A-A",rank:10},
          ],
          defaultProps: {
            children: 'children',
            label: 'name'
          }
        }
      },
      computed:{
        treeData(){
          let cloneData = JSON.parse(JSON.stringify(this.data))    // 对源数据深度克隆
          return cloneData.filter(father=>{               
            let branchArr = cloneData.filter(child=>father.id == child.parentId)    //返回每一项的子级数组
            branchArr.length>0 ? father.children = branchArr : ''   //如果存在子级，则给父级添加一个children属性，并赋值
            return father.parentId==0;      //返回第一层
          });
        }
      },
      methods:{
        handleNodeClick(data){
          // console.log(data)
          console.log(this.treeData)
        }
      },
      mounted(){
      }
    }
</script>
 
<style scoped>
 
</style>

 

const idMapping = data.reduce((acc, el, i) => {
  acc[el.id] = i;
  return acc;
}, {});

let root;
data.forEach(el => {
  // 判断根节点
  if (el.parentId === null) {
    root = el;
    return;
  }
  // 用映射表找到父元素
  const parentEl = data[idMapping[el.parentId]];
  // 把当前元素添加到父元素的`children`数组中
  parentEl.children = [...(parentEl.children || []), el];
});